Friction pads for no-spring model directional valves

ABSTRACT

A solenoid-operated valve having a free-floating, sliding spool is provided with frictional detent pins radially urged inwardly by a C-shaped spring. The pins are mounted in a cartridge member having radial bores.

United States Patent inventor Leo T. Baggy, Jr.

Birmingham, Mich.

Appl. No. 21,571

Filed Mar. 23, 1970 Patented Sept. 28, 1971 Assignee Sperry Rand Corporatio Troy, Mich. r

FRICTION PADS FOR NO-SPRING MODEL Primary Examiner-Henry T. Klinksiek Attorney-Van Meter and George DIRECTIONAL VALVES 3 Claims, 3 Drawing Figs.

US. (I 137/625.65, 251/297, 287/58, 285/302, 24/263, 248/414 lllt- A olenoid-operated vaIvg having a f 'ee-fl a[. of Search ing sliding spool provided whh frictional dgtent pins radi- 625.64, 248/414; ally urged inwardly by a C-shaped spring. The pins are 2 287/58 mounted in a cartridge member having radial bores.

so i r v 26 42 a2 20 44 I I 44 38 ill l 'l PATENTED S EP28 I97! INVENTOR. LEO T. DAGGY JR.

A M M1 ATTORNEYS FRICTION PADS FOR NO-SPRING MODEL DIRECTIONAL VALVES Solenoid-operated directional valves of the sliding spool type, such for example as illustrated in Gardiner U.S. Pat. No. 2,591,800, have solenoid push pins, or actuating plungers, through which the valve spool is pushed by the actuating solenoid. ln valves which have no biasing springs for the spool, that is, in which the spool is freely floating, a retention means is necessary to keep the spool from drifting away from its actuated position while neither solenoid is activated It is an object of the present invention to provide an improved retention means for the actuating plunger of such a valve which is simple, inexpensive and reliable in operation.

A further object is to provide such a retention means which can be mounted in a cartridge assembly surrounding the plunger. In The Drawing:

FIG. 1 is a longitudinal sectional view of a double solenoidactuated pilot valve incorporating a preferred form of the present invention.

H0. 2 is an enlarged view corresponding to a portion of HO. 1.

H6. 3 is a fragmentary sectional view taken on line 3-3 of FIG. 2.

The invention consists of a solenoid-operated fluid control valve having a body provided with a cylindrical bore intersected by axially spaced laterally extending fluid ports, and a freely floating spool slidable in the bore together with oppositely acting solenoids, each having an operating plunger arranged to actuate the spool in one direction or the other, and wherein an improved retention means is provided which comprises one or more radially movable friction pads contacting one of the plungers and a C-shaped spring surrounding the plunger and the pads to maintain a substantially fixed frictional drag on the plunger for holding the spool in whatever position it occupies at the conclusion of a solenoid actuation.

Referring now to HO. 1, the solenoid-operated directional valve comprises a main body having a central bore 12 in which is mounted a freely slidable spool 14. The usual laterally extending ports such as 16, 18, 20, 22 and 24 are variously connected for directional flow control in a well-understood manner. The spool 14 in FIG. 1 is illustrated in an intermediate position and normally occupies a position either to the right or to the left of that illustrated.

Actuating solenoids 26 and 28 are bolted to the ends of the body 10 and are provided with actuating pushpins or plungers 30 and 32 for pushing the spool 14 to the right and to the left respectively. As shown in more detail in FIG. 2, the plunger 30 has a head 34 which is received in a slot 36 in the end of the spool 14.

The bore 12 is provided with extension bores 38 and 40, each of which is closed by a closure member 42. The closure members 42 are retained in the bore extensions 38 and 40 by snaprings 44 and carry sealing rings 46 and 48 in contact with the bore extension and the plunger respectively.

The improved retention means for the actuating plungers and the valve spool includes a unitary cartridge member 50 which surrounds the plunger and is retained against the closure member 42 by a spring 52. The cartridge member 50 includes a plurality of radial stepped bores 54, each of which carries a shouldered friction pad 56. The cartridge 50 has a neck portion 58 surrounding the bores 54 for the purpose of receiving a C-shaped retaining spring 60. The spring 60 abuts the outer end of the friction pads 56 to urge them radially inward against the plunger 30. A pin 62 (FIG. 3) is pressed into the cartridge 50 and prevents displacement of the spring 60.

ln operation whenever either of the solenoids 26 or 28 is energized, the corresponding plunger 30 or 32 pushes the spool 14 to the right or to the left respectively. The plunger 30 slides through the cartridge 50, overcoming the frictional force of the retention pads 56. When the solenoid is deenergized, the C-spring 60 maintains a radially inward force on the friction pads 56 and on the spool 30. Due to the two-way connection between the plunger 30 and the spool 14 at the head 34 and the slot 36, the spool is prevented from drifting.

Preferably the plunger 30 and the friction pads 56 are made of dissimilar metals, for example hardened steel and bronze respectively. The Cspring 60 occupies a minimal amount of space and exerts a constant radially inward force on the friction pads with a high degree of reliability and durability.

I claim:

1. In a solenoid-operated fluid control valve having a body provided with a cylindrical bore intersected by axially spaced laterally extending fluid ports, a freely floating spool slidable in the bore, and oppositely acting solenoids, each having an operating plunger arranged to actuate the spool in one direction or the other, the improvement comprising a radially movable friction pad contacting one of the plungers, a C shaped spring surrounding the plunger and pad to maintain a substantially fixed frictional drag on the plunger and hold the spool in whatever position it occupies at the conclusion of a solenoid actuation and means holding the pad from axial movement in the bore.

2. The valve defined in claim 1 wherein the pad comprises a shouldered pin slidably mounted in a stepped bore, whereby the inward motion of the pin is limited sufficiently to permit initial assembly of the plunger while the spring maintains the pin in its most inward position radiallyv 3. The valve defined in claim 1 wherein the means includes an extension of the cylindrical bore adjacent to a solenoid, a plunger retention cartridge positioned in the bore extension and providing a mounting for the pad and its spring, a closure member removably mounted in the end of the bore extension, inner and outer seal rings between the closure and the plunger and the bore extension respectively, and a spring holding the cartridge outwardly against the inner face of the closure. 

1. In a solenoid-operated fluid control valve having a body provided with a cylindrical bore intersected by axially spaced laterally extending fluid ports, a freely floating spool slidable in the bore, and oppositely acting solenoids, each having an operating plunger arranged to actuate the spool in one direction or the other, the improvement comprising a radially movable friction pad contacting one of the plungers, a C-shaped spring surrounding the plunger and pad to maintain a substantially fixed frictional drag on the plunger and hold the spool in whatever position it occupies at the conclusion of a solenoid actuation and means holding the pad from axial movement in the bore.
 2. The valve defined in claim 1 wherein the pad comprises a shouldered pin slidably mounted in a stepped bore, whereby the inward motion of the pin is limited sufficiently to permit initial assembly of the plunger while the spring maintains the pin in its most inward position radially.
 3. The valve defined in claim 1 wherein the means includes an extension of the cylindrical bore adjacent to a solenoid, a plunger retention cartridge positioned in the bore extension and providing a mounting for the pad and its spring, a closure member removably mounted in the end of the bore extension, inner and outer seal rings between the closure and the plunger and the bore extension respectively, and a spring holding the cartridge outwardly against the inner face of the closure. 